Wastewaters of a manufacturing plant or the like, as discharged to an adjacent stream, may contain excessive contaminants. In an instance to which the present invention has particular application, a manufacturing plant provides rinse tanks the contents of some of which in use become contaminated with chromium and the contents of others of which become contaminated with fluorides. Contamination can rise to levels regarded as deteriorating to the environment so that used rinse water cannot simply be pumped out of the building, but must be pretreated. The use of chemical reagents to achieve a neutralizing effect is known but both an under application and an over application thereof may have undesirable results. Moreover, generalized efforts in this regard may not provide for a separation of precipitated solids. Still further, neutralizing systems as known heretofore have contemplated separate treatment of fluoride containing wastewater and of chromium containing wastewater. The former, in a typical system of the prior art, is raised to a relatively high PH level of alkalinity and allowed to stand for an extended period. The concept of continuous treatment and of treatment in the same system and at the same time as chromium contaminated wastewater has been unknown.